Magnetic speedometer



J.- K. OLSEN MAGNETIC SPEEDOMETER April 5 1927. I 7 1,623,550

Filed Sept. 1. 1922 3 Sheets-Sheet 1 NONE Mani/1' JS/m Olsem 1 623,550 April 5 1927. J. K. OLSEN MAGNETIC SPEEDOMETER Filed Sept. 1. 1922 3 Sheets-Sheet 2 T I g .7

April 5 1927.

.1. K. OLSEN MAGNETIC SPEEDOMETER Filed Sept. 1.

3 Sheets-Sheet 3 NITE-D] OFFICE.

A maii. OLSEN, or o ireaoo, rumors, nssionoafro. srnwAa'r-wanNEa-srnnnenema conronarron, or cnreaeo, rnrmolsg-n eonroaarron or VIRGINIA.

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Application filed September This invention relates to speedometers of the magnetic type. Its purpose is to provide a magnetic speedometer in which a rotating magnet of less weight than heretofore commonly employed shallexert a stronger magnetic dragupon the drag element, and in which the construction shall be more compact and economical than hitherto commonly employed,'and by reason of the superior mounting orthe method'of mounting the rotating parts shall be adapted to be drlven at a higher-speed than previous instruments of this class, further increasing the magnetic drag and permitting the use of a'stronger 1 anism in the casing.

Figure 2 and Figure 7.

biasing spring, and therefore rendering the instrument less susceptible to disturbance from exterior jarring'o'r othercauses which tend to interfere with the accuracy of the mileage indications; It consists in the fea-' tures and elements of-eonstruction shown and described as indicated in theclaims.

In the drawings v Figure 1 is a'front or face view of the instrument as a whole, same, being a com bined magnetic speedometer and odometer. Figure 2 is a front elevationof the same with thefa'ceplate and the odometer .removed showing only the speedometer mech- Figure 3 is a side view of the mechanism and support therefor shown in Figure 2, the casing being removed. g

Figure 4'is asection in part at the line, 4-4, on Fig.2 and on Fig. 7 I

Figure 5 is a'section through the casing at the line 55, on Figure 4, showing the speedometer mechanism and support in top plan view."

Figure 6 is a detail section at the line6-6 on Figure 5.

I F'gure 7 is a section. at the line, 7'7, on Figure 4. v

\ Figure 8,is a section at the'line, 8'8, on

The structure shown in the. drawings compr ses: a'sheet metal casing, A, which is of sheet;inetalistampin and is in general in cup form, that Jis,.cy indrical with a bottom or back, web. lVithin ithis casing there is mounted the speedometer support, B, which a unitary die-casting. It is is preferabl adapted to ave secured to it'the sup ort for odometer mechanism not shown, w ich when mounted. occupies -the space, C, (see Figure 3) in front of the back plate and 1, 1922. sejn wno. {585,628.

horizontal or par-axial web, B, a little above the horizontal diameter of the cylindrical outline of the casing and flange, b Theba'ek web, B, has the journal bearing boss, B for'the inleading power shaft D. The'horizontal web, B, has a journal bearlng boss, B, for the vertical shaft of the speedometer magnet and a bearing for that shaft is provided in the forward end of a boss, B, which projects from, and is an extension of the journal bearing boss, B, as seen most clearly in Figure 4. The magnet shaft, E, is tubular and has intermediate ltS said bearings a spiral gear, F, which is driven .by a spiral gear, D, on the in-leadingpower. shaft, D. The magnet, G, is of by which thelubricant is delivered to the upper bearing of the shaft, E, which is obtained in a'bearing bushing, F forced into the journal bearing boss, B A grease cavity, f is provided in the journal bearing between the ends thereof which serves to hold a limited quantity of lubricant which reaches it from the cup, G The lubricant which may flow down alon .the shaft, E,-

from said lubricant pocket, reaching the spiral gear, F, is centrifugally delivered from the upper side ofsaid gear to the mesh of said gear with its driving gear, D. Lubricant from the grease cup, G flowing by the course indicated will reach the intermeshing gears, F and D, and then passing along the shaft. E, reaches the lower bearing thereof in thebushing sleeve, F, which is pinned into the forward extension, B, above mentioned. of the journal bearing boss, B3, said bushing having at its rear side an aperture as seen at f registerin with the passage, 6, for admitting the ln ricant.v

The magnet, G, is desirably thin relatively to its width; and the diameter of its open center is small relatively to its outer diameter; that is, the magnet is a relatively flat ring so that it presents laterally to the field plate and the drag element a relatively large area from which the flux to be cut by the drag element may emanate. But for giving the maximum drag efficiency to the magnet it is desirable that the flux lines cut by the drag element shall he, in as large a. proportion as possible, near the circumference of the magnet, so as to operate with maximum radius of leverage upon the drag element. For this purpose in the first place the magnet gap is widened taperingly toward the center as seen clearly in Fi 'ure 5, said gap being quite narrow for a short portion, 9, commencing at the outer circumference and then widened taperingly for the remainder of the width of the magnet rin as seen at g. The effect of this form 0 gap is that the lines of flux passing from pole to pole tend to pass at the point of least reluctance which is at the narrow portion of the gap, and the flux is therefore concentrated at this portion of the magnet to the limit of saturation, being correspondingly diminished at the inner portion where the gap is wider. Due to the saturation at the outer portion of the magnet there are more stray lines at the outer portion which ma. be deflected -by the field plate so as to e cut by the drag element; and being thus cut at the outer circumference of the magnet the flux operates with the advantage of maximum radius leverage for drag efl'ect.

Further to increase the drag effect by causing the deflected flux to be cut by as large a cross-sectional area as possible of the drag element, the field plate, H, comprising a trans-axial web and mounted as hereinafter described has a marginal annulus, H offset from the plane of the remainder parallel thereto, forming between the main portion of the web and said annulus, a par-axial annular portion H connecting said offset annulus with the main central area of the plate, said offset annulus and said paraxial connecting annulus being dimensioned for positioning the ofl'set annulus, H encompassing the magnet at a sufficient distance radially therefrom to admit between the magnet and said encompassing portion an annular par-axial portion. K, of the dra element, K, which is produced as hereinafter more particularly described. The field plate, H, is carried in its position parallel to the up er face of the magnet y a plurality o brackcts,four being shown,L, L L and L, each made of two laminae, both bein non-ma netic and having different coefficients of expansion by heat, that of the outer lamina being the higher, so that the brackets are flexed slightly by changes of temperature, are footed on the horizontal web, B", of the support, B, as seen most clearly in Figure 5, and extend up outside the drag element, K, and thence project inward radially overhanging the field plate; and said field plate is suspended from said overhanging bracket arms by bolts, Z, which project from the field plate. and provided with securing nuts, Z above the bracket arms, springs, Z", being interposed between the field plate and the overhanging ends of the bracket arms, so that by slacking or screwing on the nuts more or less the field plate may be lowered toward or lifted from the magnet. The purpose of this feature of the construction, regardless of the adjustability indicated, is that since the-attraction of the magnet for the field plate tends to spring the bracket arms down, rise of ten'iperature and relaxing of the stiffness of the bracket arms causes the field plate to approach the magnet, and this approach compensates for the diminution of magnetic drag which results from the same rise of temperature.

The drag element is in inverted cup form having its web or bottom secured to the upper end of a spindle, N, which extends down through the hollow magnet shaft, E, and is stepped at its lower end in a bearing jewel, n, carried by a jewel cup, N, screwed through a supporting arm, N, which is bolted onto the under side of. the horizontal extension, B, which at its forward end carries the journal lower bearing of the shaft, E, as stated, the jewel cu N, protruding into the axial cavity of t e shaft, E. For the upper bearing of the spindle, N, and for stopping the same upwardly there is provided a bracket, R, footed on the web, B, intermediate the footing of the two rear brackets, L and L, said bracket, R, extending up past the drag cup, and having an arm, R, projected forward to intersect the axis of the magnet and spindle, N, and pro vided with a second arm, R parallel to the arm, R, above the same also intersecting said axis. In the arm, R, an upper bearing is provided for the spindle, N, and the upper end of the spindle is stopped under and against the upper arm, R", all as most clearly seen in Figure 4. The field plate, H, is annular and the drag cup, K, has at the center of its bottom or web an up-struck boss, la, which protrudes through the open center of the field plate. The spindle, N, is secured to the drag cup at the top of this lip-struck boss by meansof clamping collars, n and n pressed onto the spindle respectively below and above the top web of said boss, the spindle being reduced in diameter above the seat of the collar to obtain an upper bearing in the bracket arm, R.

The dra cup having its web or bottom secured as described to the spindle comprises in addition a par-axial flange or wall, K, diametered for encompassing the, magnet,

H, and the trans-axial peripheral flange,

ll, overhangs and encompasses the transaxial web and par-axial annulus, K, of the drag cup, and said flange, H overhangs the annulus, K of the drag cup, the outer diameter of said flange being substantially the inner diameter of the skirt or outer' flange,

'K, of the drag P- p considering this construction it will be seen that the three elements,ring magnet, drag element and field plate,-'are nested one within the other in the order stated; that is, the magnet being nested in the drag cup and the drag cup nested in the field plate. The purpose and effect of this construction isthat the stray lines of flux deflected by the field plate at the outer circumferential portion of the latter comprising the flange. H. and annulus, H intervening between said flange and the main web, H, are cut by an extended portion of the drag cup in the form resulting from the flexure in opposite directions from the part intermediate such flexures, said form comprising an outer circumferential portion of the web, K, the par-axial annular portion, K, and the peripheral transaxial flange, K and thereby a maximum proportion of the lines of the deflected spray flux are cut by the drag cup with the maximum radius; with the effect of obtaining from a magnet of given size and degree of saturation, the maximum drag effect.

For mounting the biasing spring, S, the bracket arm, R, has a laterally extended terminal, R and a lug, 1", up-turned therefrom, said lug being apertured for inset-tion of the outer end of the coiled spring, S, with a wedging pin, 0*, for pinning it fast at its outer end. The inner end of the spring is secured to a collet, n, pressed onto the upper end of the spindle, N. The bracket arm, R, has a forwardly projecting terminal, R, for stopping the swing of the drag element under the stress of the biasing spring at zero position, a lug, k, be-

ing struck up from the hollow boss,,k an

that purpose.

It will be observed that, taking advan tage of the depth below the plane of the rotating'magnet necessary to accommodate the odometer mechanism (not shown), the magnet is given an unusually long vertical, shaft having its bearings widely spaced apart. This has the effect of making the magnet steady itself by its own rotation,

giving it a spinning top character, and this is the purpose of this feature ofthe con struction.

In the foregoing descriptlon and in the following clalms, the terms trans-axial is formed encompassing the magnet a parand par-axial are employed with their etymological meanings, respectively, VIZ, transverse to the axis, and in the direction of'and laterally offset. from the axis.

I clann:- 1. In a magnetic speedometer comprising an axis andmounted for rotation about the a magnet element which is disposed about same axis, the width of the magnet gap being in a direction circumferential about said axis; a field plate mounted trans-axially of the magnet element'h'aving an annular marginal portion offset along the axis from the inner portion of the plate, whereby there axialannulus which is encompassed by a trans-axial annulus, and a drag element in cup form with its trans-axial web or bottom interposed between the magnet and the field plate and having its wall consisting of two flange portions with an intervening transaxial annular web, the lesser-diametered flange encompassing the magnet between the same and the par-axial annulus of the field plate, said intervening annular web being proximate to the peripheral trans-axial flange of the field-plate; whereby the flux emanating both from the periphery and the lateral margin of the magnet is concentrated for traversing the drag element at maximum distance from the axis.

2. In a magnetic speedometer in combination with a support a magnet mounted thereon for rotation about an axis, a drag element and a field late formed for circumaxially encompassing the magnet by the drag element and the drag element by the field plate, bi-metallic brackets symmetrically distributed about the axis and footed on the support radially beyond the drag elethereon for rotation about its axis, a transaxial field plate; a drag element in cup form and a spindle by which it is mounted for oscillation about the axis of the magnet with its web trans-axially interposed between the magnet and the field plate and its flange en compassing the magnet and depending therebclow, the field plate being annular and the drag element having a central up-struck bosswhich protrudes through the open center of the annular field plate for securement of. the drag element to its spindle above the field plate; a bracket of non-magneticinate' rial footed on the support outside the bracket arm, extending up and having, an arm ex! tending in above the field plate substantiall in the plane of the top of said u -strue boss, anda biasing springfor the rag element secured at one end to said bracket arm and at the other end to the drag element at a point on its spindle above the boss.

4. In a magnetic speedometer in combination with a support, a ring magnet mounted thereon for rotation about its axis, a transaxial field plate; a drag element in cup form; and a spindle by which it is mounted for oscillation about the axis of the magnet with its web trans-axiallv interposed between the magnet and the field plate, and its flan e encompassing the magnet and depen' ing therebelow, the means for carrying the field plate comprising bimetallic brackets footed on the support and having arms extending up therefrom outside the drag element and thence inward over the field plate for terminating thereabove, means for susending the field plate from said overhangmg bracket arms; whereby the direct magnetic pull of the magnet on the field plate tends to put said bracket arms under tension of flexure.

5. In a magnetic speedometer in combination with a support a magnet mounted thereon for rotation about an axis, a drag element and a field plate formed for nesting the magnet in the drag element and a drag element in the field plate, and a casing in which all said elements are nested, the field plate having a marginal transaxial annular portion, the drag element having for such nesting a par-axial annulus and a transaxial annulus encompassing it, the parts being dimensioned for locating the transaxial marginal annulus of the field plate adjacent the transaxial annulus of the drag element, the drag element havin a flange extending from the periphery 0 its said transaxial annulus forming for carrying the speed graduations, a skirt flange positioned proximate to the case wall for a proximating the reading aperture, where y the diminution of drag due to the radial ofisetting of the skirt flange for approximating the reading aperture is compensated by the co-operation of the transaxial annuli of the field plate and drag member respective.

6. In a magnetic speedometer comprising a ring magnet having an invariable gap mounted for rotation about its axis, a field plate for concentrating the stray flux, a dra element interposed between the magnet an the field plate for cutting the concentrated flux as the magnet rotates, the magnet gap being widened diametrically from a point intermediate the two circumferences to the inner circumference of the magnet.

In testimonv whereof, I have hereunto set my hand at Chicago, Illinois, this 22 day of August, 1922.

JOHN K. OLSEN. 

